Liquid Chromatography–Mass Spectrometry-Based Metabolomics for Understanding the Compositional Changes Induced by Oxidative or Anoxic Storage of Red Wines

The aim of this work was to study the physicochemical changes of eight red wines stored under conditions differing in O2 exposure and temperature and time under anoxia. The methods used to analyze the wines included the measurement of volatile sulfur compounds, color, tannin (T) polymerization, and liquid chromatography–mass spectrometry untargeted metabolomic fingerprint. After 3 months, the color of the oxidized samples evolved 4–5 times more intensively than in wines stored under anoxia. The major metabolomic differences between oxidative and anoxic conditions were linked to reactions of acetaldehyde (favored in oxidative) and SO2 (favored in anoxia). In the presence of oxygen, the C-4 carbocation of flavanols delivered ethyl-linked tannin–anthocyanin (T–A) and tannin–tannin (T–T) adducts, pyranoanthocyanins, and sulfonated indoles, while under reduction, the C-4 carbocation delivered direct linked T–A adducts, rearranged T–T adducts, and sulfonated tannins. Some of these last reactions could be related to the accumulation of reduced species, eventually ending with reductive off-odors.本研究旨在探究8款红葡萄酒在不同氧气暴露量、储存温度以及无氧储存时长条件下的理化变化。本研究采用的葡萄酒分析手段包括挥发性硫化物（Volatile Sulfur Compounds）含量测定、色泽分析、单宁（T）聚合度检测，以及液相色谱-质谱（Liquid Chromatography-Mass Spectrometry）非靶向代谢组学指纹图谱分析。储存3个月后，氧化组样品的色泽变化幅度为无氧储存组的4至5倍。氧化与无氧两种储存条件下的主要代谢组学差异，与乙醛（Acetaldehyde，氧化环境中更易生成）和二氧化硫（SO₂，无氧环境中更易留存）的反应密切相关。在有氧条件下，黄烷醇（Flavanols）的C-4碳正离子会生成乙基连接的单宁-花色苷（Tannin-Anthocyanin Adduct, T-A）、单宁-单宁（Tannin-Tannin Adduct, T-T）加合物、吡喃花色苷（Pyranoanthocyanins）以及磺化吲哚（Sulfonated Indoles）；而在还原环境中，其C-4碳正离子则会生成直接连接的T-A加合物、重排型T-T加合物以及磺化单宁（Sulfonated Tannins）。上述部分反应可能与还原态物质的积累相关，最终可能产生还原性不良风味（Reductive Off-Odors）。